1. Field of the Invention
The present disclosure generally relates to a developer amount regulation blade structure used in an image forming apparatus, for example, printers, facsimiles, copiers, and multifunctional machines including functions of printer, facsimile, and copier.
2. Discussion of the Related Art
A conventional image forming apparatus has a developing apparatus which includes a developer bearer (a developing roller) and a developer amount regulation blade structure. The developer bearer (developing roller) attracts a two-component developer including a toner and a magnetic carrier or a one-component developer including a toner by magnetic force of a magnet roller and supplies the developer to a latent image bearer. The developer amount regulation blade structure faces the developer bearer and supplies the developer to the latent image bearer. A regulation blade, which is a thin board member, is provided on the developer amount regulation blade structure.
The regulation blade regulates the amount of the developer supported on the surface of the developer bearer. In a one-component type developer, for example, the regulation blade such as blade springs is pressed against the surface of the developer bearer. Therefore, the amount of the developer on the surface of the developer bearer is regulated by the regulation blade.
As with the developing apparatus, in order to make the developer bearer be supplied uniformly with the developer in a longitudinal direction of the developer bearer, it is necessary that the regulation blade be pressed with a uniform force in the longitudinal direction. Therefore, uniform flatness is required of the regulation blade.
FIG. 1 is a cross-sectional diagram illustrating an exemplary configuration of a developer amount regulation blade structure of a conventional image forming apparatus. As shown in FIG. 1, a supporting member 2 faces a developer bearer 1. Screws 4 located along a regulation blade 3 fix the regulation blade 3 on the supporting member 2. The regulation blade 3 is in touch with the surface of the developer bearer 1 by a given pressing force F.
However, this type of the regulation blade 3 has a waveform in the longitudinal direction, and therefore fails to achieve the straight edge intended by design. As a result, a gap between the developer bearer 1 and the regulation blade 3 is uneven and consequently good frictional electrification is not obtained, resulting in production of defective images in image formation.
For the straightness of the edge of the regulation blade 3, it is considered that it is good to increase the pressing force F. However, the increase of the pressing force F may cause the regulation blade 3 to scratch the developer bearer 1, in which case a lifetime of the development bearer 1 may decrease.
To fix this problem, a developer amount regulation blade structure in which a bolting torque gradually decreases toward a center of the regulation blade 3 from the both ends thereof when the regulation blade 3 is fixed on the supporting member 2 is proposed.
In addition, a developer amount regulation blade structure in which a thin regulation blade is fixed on the supporting member 2 by welding is also proposed.